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Eight crab species (Eriphia verrucosa, Maja squinado, Calappa granulata, Charybdis (Goniohellenus) longicollis, Callinectes sapidus, Atergatis roseus, Portunus segnis, Maja crispata) were sampled from Mersin Bay (Northeastern Mediterranean) between September 2017 and April 2018. Three species belong to the family of Portunidae while two Maja species represent Majidae. The other crabs represent the families of Calappidae, Xanthidae, and Eriphidae. All specimens were preserved in ethanol and were deposited in the Museum of the Systematic, Faculty of Fisheries, Mersin University (catalogue number:MEUDC-17-12-002 - MEUDC-18-12-009). Previous records of these crabs in the Mediterranean Sea were determined as their distributions were compared. All crab samples in the study are distributed in the Northeastern Mediterranean Sea commonly.&nbsp

The paper presents a review of the distribution of marine crabs (Brachyura) along the Turkish coast and the amount of economically important marine crabs harvested between 1967 and 2016. Previous records reported that Turkey had 102 brachyuran crab species, only five of them being economically important, but this review identifies two more species, Inachus phalangium and Ashtoret lunaris. The Aegean Sea has more crab species than the Mediterranean, the Black Sea and the Sea of Marmara. The most harvested species are Callinectes sapidus, Maja squinado, Eriphia verrucosa, Carcinus aestuarii and Portunus segnis, respectively. This review shows that there have been fluctuations in the harvest of marine crabs between years, the lowest being 5 tonnes in 2015 and the highest, 2116 tonnes in 1984. The information provided in this review provides a basis for potential profitable development of conservation and management strategies of marine crabs in Turkey.

Microplastic pollution is apparent throughout the marine environment from deep ocean sediments to coastal habitats. Most of this is believed to originate on land, although marine activities, such as fishing and shipping, also contribute to the release and redistribution of microplastic. The relative importance of these maritime plastic sources, the manner by which they are distributed in the environment, and their effect on uptake by marine organisms are yet to be fully quantified. In this study, the relative impact of fishing activities on microplastic uptake by demersal fish and crustaceans was explored. Local fishing intensity, proximity to land and mean water velocity are compared to microplastic uptake in plaice, Pleuronectes platessa, and spider crab, Maja squinado, from the Celtic Sea. Observations were also made of microplastic contamination in ingested sand eels, Ammodytes tobianus, to establish a potential route of trophic transfer. This study is the first to identify microplastic contamination in spider crab and to document trophic transfer in the wild. Individuals were sampled from sites of varied fishing intensity in the Celtic Sea, and their stomach contents examined for the presence of microplastic. Contamination was observed in 50% of P. platessa, 42.4% of M. squinado, and 44.4% of A. tobianus. Locations of highest plastic abundance varied between P. platessa and M. squinado, indicating that different factors influence the uptake of microplastic in these two taxa. No significant link was observed between fishing effort and microplastic abundance; however, proximity to land was linked to increased abundance in M. squinado and Observations of whole prey demonstrate ongoing trophic transfer from A. tobianus to P. platessa. The lack of significant difference in microplastic abundance between predator and prey suggests that microplastic is not retained by P. platessa.

The Mediterranean spider crab, Maja squinado (Herbst, 1788), is of increasing interest for commercial or stock enhancement purposes, which necessitate the production of a large number of specimens in captivity. However, the growth and survival of crabs during the early juvenile phase could be affected or limited by several factors. In this study, the effects of stocking individually or in pairs, diet, shelter presence and shelter type for juveniles (from 2nd to 5th juvenile crab instar) were investigated. Survival was higher for the group with two individuals per cylinder than the group with one individual per cylinder, but the growth (carapace length and intermoult period) was not significantly different. The tested diets (fresh and dry diets) did not produce significant differences in growth, but the dry diet resulted in a higher survivorship at the end of the experiment (75%) than the fresh diet (47.5%). Finally, the presence of shelter was clearly beneficial for the groups with two individuals per cylinder, mainly in the case of natural shelter. Crabs in natural shelter had a higher survival rate (55%) and were larger, probably due to the consumption of the algae added as shelter. Thus, this study is a first approach to find the optimal rearing conditions that maximizes the production of juveniles during an especially vulnerable phase., Financial support was provided by JACUMAR, Secretaria General de Pesca Maritima, Spanish Goverment (“Cultivo de la centolla” and “Propuestas y mejoras para el diseño de los planes de repoblación y evaluación de los impactos de los escapes” projects), and by the Goverment of the Balearic Islands.

Until recently it was not thought possible to directly and accurately age crustacean species as any calcified structure that could preserve a record of chronological age is lost at moulting. Recent research has suggested that it may be possible to directly infer age from the number of endocuticular bands present within the eyestalks of snow crab (Chionoecetes opilio) and Antarctic krill (Euphausia superba). Using captive-reared Mediterranean spider crabs (Maja squinado), and wild-caught north-east Atlantic spider crabs (Maja brachydactyla), the present study aimed to determine if endocuticular bands of potentially annual periodicity are present within the eyestalks of these brachyurans. Although clear and readable bands were present within the endocuticle of their eyestalks, no bands of potentially annual periodicity were identified. The number of endocuticular bands did not correlate with the known-age of the M. squinado individuals; but did correlate positively with carapace length for both M. squinado and M. brachydactyla, suggesting they form as a result of growth and the size of individuals. It is hypothesised that these endocuticular bands, and potentially those identified by other studies purporting them to be annual growth bands, are in fact lamellae that appear due to the layers of calcite crystal aggregates interspersed with chitin and protein fibres that form the mineral of the cuticle in decapod crustaceans. Further research is needed to determine the processes that control and result in the deposition of crustacean cuticle, particularly during the post-moult period.

We sequenced the mitochondrial genomes of the spider crabs Maja crispata and Maja squinado (Majidae, Brachyura). Both genomes contain the whole set of 37 genes characteristic of Bilaterian genomes, encoded on both α- and β-strands. Both species exhibit the same gene order, which is unique among known animal genomes. In particular, all the genes located on the β-strand form a single block. This gene order was analysed together with the other nine gene orders known for the Brachyura. Our study confirms that the most widespread gene order (BraGO) represents the plesiomorphic condition for Brachyura and was established at the onset of this clade. All other gene orders are the result of transformational pathways originating from BraGO. The different gene orders exhibit variable levels of genes rearrangements, which involve only tRNAs or all types of genes. Local homoplastic arrangements were identified, while complete gene orders remain unique and represent signatures that can have a diagnostic value. Brachyura appear to be a hot-spot of gene order diversity within the phylum Arthropoda. Our analysis, allowed to track, for the first time, the fully evolutionary pathways producing the Brachyuran gene orders. This goal was achieved by coupling sophisticated bioinformatic tools with phylogenetic analysis.

The present study is a characterization of the chemical composition of crab shells from brown crab, spider crab, velvet crab and green crab. The chitin content of crab shells varied between 9.7 and 16.4% and the protein content was in the range of 13.2 to 20.7%. Ash was the major constituent and accounted for more than 70%. The total carotenoid content ranged between 0.6 and 9.3 μg/g depending on the crab species. Concerning macro elements their content followed the descending order in all species: Ca>P>S>Sr>Cl>K. In the case of trace elements content the descending order in brown crab was: Br>Fe>Rb>Cu>Zn; in spider crab was: Br>Fe>Rb>Zn>Cu and in velvet and green crab was: Br>Fe>Zn>Rb>Cu. The level of contaminants was relatively low and the descending order of their content was the following: As>Pb>Cd>Hg. Crab shells are a potential source of chitin and the levels of macro and trace elements together with the low contaminants concentration make them a raw material for chitin production or utilization as feed ingredients or fertilizers.

9 pages, 4 figures, 1 table, The spider crab Maja squinado is restricted to the Mediterranean Sea, and as captures of this species became very rare in the last decades, it is a protected species. To improve spider crab production in experimental or commercial hatcheries and allow the future success of restocking programmes, knowledge of larval growth and biochemical characteristics is mandatory. In the present study, larvae from 4 different batches were studied. Larvae were examined to determine the larval instar and moulting stages. In each moulting stage for all larval instars, carapace length, dry weight, ash and proximal composition (protein, carbohydrates and lipids) were measured. Metamorphosis began at 14 d posthatching (dph), with metamorphosis to the first juvenile crabs completed in about 90% of the specimens at 17 dph. Survival dropped from 59.25 ± 19.53% to 33.49 ± 19.53% between the zoea II and megalopa stages, and only 7.74 ± 1.94% of newly hatched larvae (NHL) reached the first juvenile crab stage. NHL weighed 120.40 ± 18.95 µg, increasing their dry weight and ash content 6-fold after metamorphosis. Dry weight also increased through the moulting cycle in each larval instar, while ash content was higher in early premoult stages. Proximal composition increased between 8- and 6-fold from NHL to megalopa in the premoult stage and then decreased 2-fold during metamorphosis. Lipid and protein content varied among moulting stages from the postmoult to the premoult stages, with more significant alterations seen during the megalopa instar stage, Bench fees were provided by Junta Asesora de Cultivos Marinos (JACUMAR) (REPES project) to G.R. Financial support was provided by the Ministry of Science and Research to G.G. (post-doctoral fellowship; Instituto Nacional de Investigación y Tecnología Agraria Alimentaria)

In this paper, we report the first successful attempt to grow Maja squinado in captivity from larvae to sexual maturity. Eggs were obtained from wild-caught crabs in the laboratory. The larvae-juveniles were reared together to an age of 150-210days. Subsequently, up to seven consecutive molts were individually monitored to an age of 490days maximum. Based on these individually monitored crabs, a growth model was developed to predict the molting probability and molting increment as a function of sex, temperature, and pre-molt size. The predictions of the model show that the females (25-75% percentiles of the 7th monitored molt: 106 to 139mm and 456 to 654days) appear to have a lower but less variable growth rate than the males (98 to 152mm and 378 to 518days). The size at first maturity for females was estimated to be 103.6mm. Although the model was parameterized using individuals raised in aquaculture, data and models of this type are very scarce for crustaceans and will be useful for managing the ongoing stocking program for M. squinado in the Balearic Islands. In addition, the full life cycle of the Mediterranean spider crab was completed in captivity. The mating of laboratory-reared crabs was repeatedly observed, and viable eggs and larvae were obtained from laboratory-reared adults. © 2013 Elsevier B.V., Financial support was provided by JACUMAR (“Cultivo de la centolla” and “Propuestas y mejoras para el diseño de los planes de repoblación y evaluación del impacto de los escapes” projects) and by the Government of the Balearic Islands

The macrofauna assemblages of a XVIIth century shipwreck off southern Portugal were studied and compared with those of nearby natural reefs and sandy bottoms, by underwater visual census. A total of 11 173 specimens of 224 different fauna taxa and 12 phyla were recorded. Natural reefs had the highest density of specimens (35 122 / 1000 m²) followed by the shipwreck (21 392 / 1000 m²) and the sandy bottoms (3771 / 1000 m²). Three biodiversity indices were estimated (Margalef, Shannon-Wiener and Pielou), with the natural reefs showing the highest values. However, the shipwreck presented values relatively similar to those of the natural reefs for the Shannon-Wiener and Pielou indices. The three habitats were clearly distinguishable by multivariate statistical analysis, with the average dissimilarity between sand and shipwreck, and between sand and natural reefs being much higher than that between the shipwreck and the natural reefs. The shipwreck had higher abundances of some commercially important species, such as the pouting Trisopterus luscus, European conger Conger conger, and common spider crab Maja squinado, as well as some vulnerable and threatened species such as the pink seafan Eunicella verrucosa. The results presented emphasize the importance of this habitat on the southern Portuguese coast.As comunidades de macrofauna de um naufrágio do século XVII ocorrido ao largo da costa Sul de Portugal, foram estudadas e comparadas com recifes naturais e fundos de areia através de census visuais subaquáticos. Foram registados 11 173 espécimes pertencentes a 224 taxa faunísticos e 12 phyla. Os recifes naturais apresentaram a maior densidade de espécimes (35 122 / 1000 m²) seguidos do naufrágio (21 392 / 1000 m²) e dos fundos de areia (3771 / 1000 m²). Foram calculados três índices de biodiversidade (Margalef, Shannon-Wiener e Pielou), com os recifes naturais que apresentarem os valores mais elevados. No entanto, o naufrágio mostrou valores relativamente semelhantes aos fundos rochosos nos índices de Shannon-Wiener e Pielou. Os três habitats foram separados por estatística multivariada, com a dissimilaridade média entre areia e naufrágio, e entre areia e recifes naturais sendo muito superior à dissimilaridade entre os recifes naturais e o naufrágio. O naufrágio apresentou elevada abundância de algumas espécies comercialmente importantes, como a faneca Trisopterus luscus, o safio Conger conger e a santola Maja squinado, assim como de espécies vulneráveis e ameaçadas como a gorgonia rosa Eunicella verrucosa. Os resultados apresentados realçam a importância desse habitat para a costa Sul de Portugal.

Differences in the resource use patterns of males and females of the spider crab species Maja brachydactyla Balss, 1922 and M. squinado (Herbst, 1788) from several geographic areas (three in the Atlantic and two in the Mediterranean) were studied through the analysis of stable isotopes of carbon and nitrogen in the exoskeleton of post-pubertal (adult) specimens. Results confirmed that males and females from the same population usually did not differ in δ15N values and hence foraged at the same trophic level. In contrast, females were usually enriched in 13C as compared with males from the same population, thus suggesting that females use shallower habitats than males before the terminal moult. The results reported here also indicate that stable isotop., Se estudiaron mediante el análisis de isótopos estables de carbono y nitrógeno en el exoesqueleto de ejemplares adultos las diferencias en los patrones de uso de recursos de los machos y las hembras de los cangrejos Maja brachydactyla Balss, 1922 y M. squinado (Herbst, 1788) procedentes de varias zonas geográficas (tres en el Atlántico y dos en el Mediterráneo). Los resultados confirmaron que los machos y las hembras de la misma población, por lo general, no difieren de los valores de δ15N y por lo tanto se alimentaban en el mismo nivel trófico. En contraste, las hembras por lo general se hallan enriquecidas en 13C en comparación con los machos de la misma población, lo que sugiere que las hembras ocupan hábitats menos profundos que los machos antes de la muda terminal. Los resultados aquí presentados indican también que los isótopos estables pueden ser útiles para la trazabilidad de las especies comerciales del género Maja, pero sólo si la identidad de la especies y el sexo del ejemplar se incorporan al análisis.

The Mediterranean spider crab, Maja squinado, is depleted due to overfishing. The crab has virtually disappeared from areas where it was abundant, such as the Balearic Islands and the Catalan coast. Maja squinado, is economically and ecologically very valuable, and it is essential to obtain information on its biology and rearing conditions to attempt to repopulate the damaged stocks of the species in the Mediterranean basin. Herein, we describe the first successful rearing of M. squinado under laboratory conditions. Our results show that M. squinado is an excellent candidate for restocking using cultured juveniles. Two consecutive broods with a 1–4 day interbrood period were observed in the laboratory in wild-caught females, the maximum observed duration of embryonic development of the egg mass being 32 days at 18.4 ± 0.9°C, and went through four different stages. The complete larval and first juvenile development was studied in laboratory cultures fed enriched Artemia metanauplius. At 19.6 ± 0.6°C, development from hatching to first crab moult took 17 days, and it comprised two zoeae stages and one megalopa stage. The survival rate at the different stages was monitored, and 7.13 ± 2.3% was achieved at the first crab instar.

The culture of common octopus (Octopus vulgaris), one important candidate to the aquaculture diversification, faces significant difficulties, mainly related with an inadequate first development stages diet. A mathematical model integrating disperse information on the nutrient composition throughout the species ontogenic development as well as on the effects of broodstock feeding and diet composition data of O. vulgaris, allowed us to predict the time evolution of paralarvae nutritional composition in terms of protein and lipid fractions and to design an optimal diet composition with the objective to ensure the maximal survival. The optimization routine showed that a diet based on the spider crab (Maja squinado) zoea composition is the most suitable for reaching the best survival rates. Results are verified by comparison with available experimental data. The obtained results and the prospective developments are a good example of how the systemic, quantitative model based approach can be used to analyse and contribute to the understanding of complex biological systems. info:eu-repo/semantics/publishedVersion

The morphology of the different larval stages (zoea I, zoea II and megalopa) of the majid crab Maja squinado Herbst, 1788 reared under laboratory conditions is described. The description of M. brachydactyla Balss, 1922 larvae is also revised, both from individuals reared in laboratory conditions and those collected from plankton samples. The larval stages of M. squinado are morphologically similar to those of the Atlantic species M. brachydactyla; the larval morphology does not justify the separation of M. squinado into two species. Larvae of M. brachydactyla obtained from the wild were similar to those reared under laboratory conditions. The morphology of the zoeal and megalopal stages of M. squinado and M. brachydactyla described in this paper have been compared with previous descriptions of the genus Maja, including M. brachydactyla (described as M. squinado).

Rotllant, Guiomar ... et. al.-- 12 pages, 4 figures, 3 tables, Artificial reef areas can be used for management and conservation of commercially exploited crustacean decapods but their behaviour in these environments is poorly characterised. Acoustic tags were used to study the behaviour of 3 adult spiny lobsters (Palinurus mauritanicus) and 3 adult spider crabs (Maja squinado) over a period of 64 days in summer, evaluating the use of artificial reef areas as suitable sites for re-stocking of overfished decapods. For this purpose, animals were released in a western Mediterranean artificial reef located at 20 m depth, close to a cabled seafloor observatory, which simultaneously recorded temperature, salinity, current direction, current speed and light intensity over the study period. Spiny lobsters lingered in the reef area, whereas the spider crabs left the area 21–45 h after release. These behavioural differences suggested that artificial reefs might be a good area to deploy adult lobsters for re-stocking purposes. The movements displayed by the lobsters during this experiment were not influenced by any of the measured environmental factors, whereas spider crab movements occurred against major current direction, when current speed was intense. © 2014, Springer International Publishing Switzerland, This work was supported by the Spanish Ministry of Economy and Competitiveness under the research project: ‘‘Redes de sensores submarinos acu´sticos aplicados al seguimiento de especies de interes comercial’’ (TRA2009_0294) to AM and to National Sea Harvest Advisory Board (JACUMAR) belonging to the Ministry of Agriculture, Food and Environment under the research project: ‘‘Propuestas y mejoras para el disen˜o y control de los planes de repoblacio´n y evaluacio´n del impacto de los escapes—REPES’’ to GR. [...] Jacopo Aguzzi is a fellow within the Ramón y Cajal Program (MICINN)

Research surveys were conducted monthly between July 2002 and June 2003 along the coast of Iskenderun Bay. A total of 1746 crabs were captured at 6 localities in depths of 4 to 50 m. Twenty different species were identified. Among these, Atergatis roseus (Ruppell, 1830), Charybdis helleri (A. Milne-Edwards, 1867), Charybdis longicollis Leene, 1938, Ixa monodi Holthuis & Gottlieb, 1956, Myra subgranulata Kossmann, 1877, and Portunus pelagicus (Linnaeus, 1758) are of Indo-Pacific origin. Nine species, Dromia personata (Linnaeus, 1758), Eriphia verrucosa (Forskal, 1775), Ethusa mascarone (Herbst, 1785), Liocarcinus depurator (Linnaeus, 1758), Liocarcinus navigator (Herbst, 1794), Macropodia rostrata (Linnaeus, 1761), Maja squinado (Herbst, 1788), Pachygrapsus marmoratus (Fabricius, 1787), and Portumnus latipes (Pennant, 1777) were recorded for the first time from this bay. The most abundant species found in the bay were Charybdis longicollis, Portunus pelagicus, and Callinectes sapidus Rathbun, 1896. Des suivis mensuels ont ete realises entre juillet 2002 et juin 2003 le long de la cote de la baie d'Iskenderun. Un total de 1746 crabes ont ete captures dans 6 localites a des profondeurs de 4 a 50 m. Parmi ceux-ci, Atergatis roseus (Ruppell, 1830), Charybdis helleri (A. Milne-Edwards, 1867), Charybdis longicollis Leene, 1938, Ixa monodi Holthuis & Gottlieb, 1956, Myra subgranulata Kossmann, 1877, et Portunus pelagicus (Linnaeus, 1758) sont d'origine indo-pacifique. Neuf especes, Dromia personata (Linnaeus, 1758), Eriphia verrucosa (Forskal, 1775),Ethusa mascarone (Herbst, 1785), Liocarcinus depurator (Linnaeus, 1758), Liocarcinus navigator (Herbst, 1794), Macropodia rostrata (Linnaeus, 1761), Maja squinado (Herbst, 1788), Pachygrapsus marmoratus (Fabricius, 1787) et Portumnus latipes (Pennant, 1777) ont ete identifies pour la premiere fois dans cette baie. Les especes les plus abondantes rencontrees dans la baie etaient Charybdis longicollis, Portunus pelagicus, et Callinectes sapidus Rathbun, 1896.

Over the course of the moult cycle ofMaja squinado, the spider crab changes in the hardness and colour of the carapace were assessed and used as methods to identify the intermoult stage in each individual. This intermoult staging was later verified by means of the microscopic observation of the maxilla. These staging techniques made it possible for the prompt identification of the principal intermoult stages—postmoult, intermoult and premoult. In 90% of the cases analysed, there was a correlation between the presence of an underlying carapace and a pink colour of the abdominal vein in crabs in advanced premoult stages.The seasonality of the moult was studied based on the number of specimens in the postmoult stage. There were two main moulting periods—the first occurring in April, and the second, longer period was between July and November. A hypothetical growth model was established and growth rates were determined by length–frequency distribution analyses. Three groups of juveniles and one group of adults were identified. The adults were only found among the population between July and October. In both males and females, the moult increment rate was lower in terminal moults (mean=22%) than in juvenile or prepubertal moults (mean=27%).

Migrations play a key role in the life history of the spider crab Maja squinado (Herbst, 1788) and affect fishery catches. Migrations involve important changes in depth and in the environment. Ultrasonic telemetry has a number of drawbacks due to the difficulties in the continuous tracking of crabs while they are moving to deep waters. The recent introduction of electronic data storage or archival tags permits continuous monitoring of depth and temperature in crab's habitat and reconstruction of the movement patterns using baseline data on habitat characteristics. On the Galician coast (NW Spain) we calibrated and used electronic tags as a tool to study spider crab migrations. In the summer of 1996, 17 crabs were tagged with both ultrasonic transmitters and electronic tags. Tracking was carried out discontinuously at intervals of approximately 1 wk. We obtained a recapture rate of approximately 70%. The information provided by telemetry and electronic tags indicates autumn migrations along the ba...

Marine mites belonging to the family Halacaridae were found associated with adult females of the spider crabs Maja brachydactyla Balss, 1922 and M. squinado (Herbst, 1788) held under laboratory conditions. Morphological study of collected samples identified the mites as Copidognathus stevcici Bartsch, 1976. C. stevcici was found on pleopods of ovigerous and post-ovigerous females in both crab species, with an intensity ranging from 10 to 326 mites per host. Mites were observed alive on their host for extended periods and direct evidence of feeding on crab's eggs is provided. The COI mtDNA sequence of these mites is reported as an addendum to the species description.

Geographic distribution limits of ectothermal animals appear to be correlated with thermal tolerance thresholds previously identified from the onset of anaerobic metabolism. Transition to these critical temperatures was investigated in the spider crab ( Maja squinado) with the goal of identifying the physiological processes limiting thermal tolerance. Heart and ventilation rates as well as Po2in the hemolymph were recorded on-line during progressive temperature change between 12 and 0°C (1°C/h) and between 12 and 40°C (2°C/h). Lactate and succinate were measured in tissues and hemolymph after intermediate or final temperatures were reached. High levels of hemolymph oxygenation suggest that an optimum range of aerobic performance exists between 8 and 17°C. Thermal limitation may already set in at the transition from optimum to pejus (pejus = turning worse, progressively deleterious) range, characterized by the onset of a decrease in arterial Po2due to reduced ventilatory and cardiac performance. Hemolymph Po2values fell progressively toward both low and high temperature extremes until critical temperatures were reached at ∼1 and 30°C, as indicated by low Po2and the onset of anaerobic energy production by mitochondria. In conclusion, the limited capacity of ventilation and circulation at extreme temperatures causes insufficient O2supply, thereby limiting aerobic scope and, finally, thermal tolerance.

The diet of the spider crab, Maja squinado, was studied in the rocky subtidal areas of the Ría de Arousa (Galicia, north-west Spain), by analysing the gut contents of crabs caught in the summer and winter of 1992. The highly diverse diet was made up primarily of macroalgae and benthic invertebrates that were either sessile or had little mobility. The most important prey were the seaweeds Laminariaceae (43% of the frequency of occurrence and 15% of the food dry weight), Corallina spp. (38% and 3%), molluscs [the chiton Acanthochitona crinitus (15% and 1%), the gastropods Bittium sp. (30% and 2%), Trochiidae and others and the bivalve Mytilus sp. (32% and 12%)], echinoderms [the holothurian Aslia lefevrei (32% and 18%) and the echinoid Paracentrotus lividus (16% and 7%)] and solitary ascidians (18% and 6%). The variability in diet composition was determined by the season (Laminariaceae, Corallina spp., P. lividus, Mytilus sp., gastropods and chitons appeared in greater frequency in winter, while the solitary ascidians and A. lefevrei were consumed to a greater extent in summer) in addition to sexual maturity (prey such as Bittium sp. or Trochiidae were more common in juveniles). Moreover, the changes in the food consumption rate were linked primarily to the moult stage. Feeding activity plummeted during the phases immediately preceding and following ecdysis (stages D0–D3–4 and A), and the diet was less diverse during these phases. No feeding differences were found that could be linked to sex. The composition of the diet of Maja squinado appears to be determined by the seasonal abundance of the different prey in subtidal rocky areas and by their availability (depending on their behavioural and anatomical characteristics, mainly mobility and the presence of hard external structures). Moreover, life history factors have little importance in the variability of the diet composition and only the moult cycle has a considerable effect on feeding rate.

Ontogenetic changes in the relative growth of males and females of the spider crab Maja squinado were analyzed and related to their reproductive (maturity) status in order to define criteria to assign individuals to each growth phase. The sampling was carried out in two different areas of southern Galician waters, northwestern Spain, in shallow water ( 20 m) with soft bottoms (adult habitat). A Principal Component Analysis (PCA) of morphometric variables and a nonhierarchic K-means cluster of PCA scores differentiated two morphometric groups defined as juvenile and adult phases. A significant change in allometry of cheliped size was detected in juvenile males with a break point at a 109-mm carapace length (CL). This point may indicate a change in the relative growth of juveniles, separating the immature and adolescent phases. Histological analysis of a subsample of males showed that sperm were present in most adolescent crabs, but not in immature crabs. Bivariate morphometric linear discriminant functions allow for the identification of juvenile and adult males (classified previously by K-means cluster) with over 99% correct classification using CL and the length or height of the right cheliped. Carapace length at the onset of sexual maturity was estimated to be 132.7 mm (50% of adult males), although in a broad range, 112-165 mm, the size of juveniles and adults overlap. The life history of male spider crabs shows 3 phases differentiated by the relative growth rate of chelipeds separated by two 2 critical molts: prepubertal molt (immature-adolescent) determines a slight increase in allometry, and pubertal or terminal molt (adolescent-adult) determines an increase in the relative size and allometry of chelipeds and the onset of functional maturity. Females showed only 2 phases separated by the terminal molt. Growth of chelipeds in females showed no changes in allometry and was similar to juvenile males. Juvenile females presented a smaller relative width and a higher allometry of the abdomen with regard to adult females. Unlike juvenile females with a flat abdomen, adult females with a domed abdomen have well-developed pleopods, gonads, and seminal receptacles. Carapace length at the onset of sexual maturity was estimated to be 130.4 mm (50% of adult females). The range of overlap of the size of juveniles and adults (114-143 mm) was smaller than in males. The spider crab Maja squinado (Herbst) inhabits the Northeast Atlantic from the British Isles to Guinea and the Mediterranean Sea (de Kergariou, 1984; Le Foll, 1993). It is subject to an intense fishery, especially in the waters along the coast of the English Channel and Galicia, northwestern Spain. As for other species of the Majidae, the postlarval life history of Maja squinado consists of two main phases, growth and reproduction, which are separated by a terminal molt (Vernet-Cornubert, 1958; Hartnoll, 1963, 1978; Conan and Comeau, 1986; Comeau and Conan, 1992; Meyer, 1993; Gonzalez-Gurriaran et al., 1995; Freire et al., in press). The first morphometric study done on this species (Teissier, 1935) distinguished three main developmental phases in males, separated by two critical molts. In males, the most obvious morphological change throughout growth is the development of the chelipeds. This led morphometric studies to be based primarily on changes in relative growth rates, or allometric levels, of different variables measuring the size of the chelipeds. Females undergo changes in morphology and in the allometry of the width of the abdomen. Later, these changes in external morphology were used in growth and maturity studies of other species of the Majidae (Vernet-Cornubert, 1958; Hartnoll, 1978; Conan and Comeau, 1986). In studies carried out on other majids, the different phases of the life history and critical molts were based on morphological, morphometric, physiological (gonad maturation), and behavioral criteria (Fig. 1). In males, the first postlarval phase, known as immature or juvenile, gives rise to a second phase, known as prepubertal, juvenile, or adolescent, after a prepubertal, pubertal, or juvenile molt.

To assess the respiratory physiology of marine crabs in situ, velvet swimming crabs, Necora puber, edible crabs, Cancer pagarus, and spider crabs, Maja squinado were sampled in the sublittoral zone by subaqua divers. Measurements included routine rates of oxygen uptake (ṀO2) and analysis of oxygen levels and acid–base variables of haemolymph samples withdrawn from crabs immediately after capture and analysed on the shore. Samples were then transported back to the laboratory for analysis of ion and metabolite levels along with in vitro determinations of maximum oxygen carrying capacity, protein and haemocyanin concentrations. Mean values for the major respiratory variables seemed to depend on the routine rates of activity of each species, with N. puber, an active swimming crab, characterised by the highest ṀO2, circulating oxygen levels, and oxygen carrying capacities. Haemolymph PCO2 values and lactate levels were the lowest measured, indicating high ventilation rates and a lower anaerobic component to metabolism. In comparison, M. squinado, a relatively inactive, slow moving crab, had the lowest ṀO2, haemolymph oxygen levels, and oxygen carrying capacity. Haemolymph PCO2 values were the highest, indicating a low ventilation rate while lactate levels were relatively high indicating a high level of anaerobic metabolism. The relatively slow moving, crepuscular crab, C. pagurus had intermediate values for all the variables studied. Despite differences in absolute levels of oxygen carrying capacity the majority of oxygen transported in the haemolymph was bound to haemocyanin in all three species, with high levels of % saturation in both post (80–85%) and prebranchial (50–63%) haemolymph. The amount of oxygen delivered to the tissues was proportionally higher in N. puber reflecting the high oxygen demand and aerobic scope of this species. There was a close positive correlation between maximum oxygen carrying capacities and protein, Cu2+ and haemocyanin levels in all three species. Circulating [Mg2+] levels reflected interspecific differences in routine activity with lower [Mg2+] values in N. puber compared to C. pagurus and M. squinado. In general, the respiratory variables obtained from animals sampled in situ differed from the measurements taken from crabs held in the laboratory. This investigation emphasises the importance of in situ studies to characterise routine levels of oxygen uptake, oxygen transport and acid–base status in crabs.

The spider crab Maja squinado (Herbst, 1788), reveals considerable morphological variability. This study establishes that Mediterranean populations are separable from those of the Atlantic by morphological and biometrical characters. Consistent, nonclinal morphological character differences of first gonopods and carapace spinulation, and results of multivariate analyses of morphometric measurements justify the recognition of two different species: the Mediterranean Maja squinado (Herbst, 1788) and the Atlantic Maja brachydactyla Balss, 1922. Morphological investigations of Maja capensis Ortmann, 1894—another very similar species from Namibia and South Africa—suggest that its status is rather questionable, due to partial overlap of characters with the Northeast Atlantic species. However, few Maja capensis specimens are available for study and therefore it remains at species rank until more material is available for further study.

The reproductive biology of the spider crab Maja squinado was analyzed based on monthly samples from an 18-month study carried out in Galicia (NW Spain) and laboratory experiments holding primiparous and multiparous females in captivity with and without males. The seminal receptacles of adult females were analyzed and their relationship with the presence and developmental stage of the eggs and the gonad maturity stage was determined. Gonad maturation in primiparous females began one or two months after the pubertal moult. Females having gonads in an advanced stage of development made their appearance in December and the first spawning took place in mid-winter or early spring. The percentage of ovigerous females from March to September was ∼75%. As the incubation period progressed, the ovaries became mature again in order to carry out the next spawning. Under experimental conditions the breeding cycle started earlier in multiparous females, during their second yearly cycle, than in primiparous ones. After mating, female spider crabs store sperm in seminal receptacles and this sperm is used in the fertilization of eggs immediately prior to spawning. The analyses of seminal receptacles consisted of the estimation of fullness and the number of differentiated sperm masses. The number of masses ranged between 0 and 6 in field samples (median for females with stored sperm=1) and was positively correlated with fullness. Differences in colour and volume of individual masses showed that, at least in some cases, females carried out successive matings with long intervals in between. This storage mechanism allowed females to fertilize successive broods without remating (as was also shown under experimental conditions). Juvenile females from shallow waters did not have developed seminal receptacles which indicated that mating was not possible until the onset of maturity. Postpubertal females in shallow waters (August to October), including animals participating in aggregations, always showed empty receptacles. The seasonality of receptacle fullness showed that mating involved hard-shelled females and occurred in deep water during the autumn migration from juvenile habitats or in the wintering habitats, during the last stages of gonad maturation (November to February). After fertilization ovigerous females continued to store sperm, but the volume was lower than in non-ovigerous females. Mating may occur in ovigerous females, particularly in the final period of incubation, because in females with broods almost ready to hatch, both new and older sperm masses were seen in the receptacles (distinguished by colour and size). The fullness of the receptacles decreased both in ovigerous and non-ovigerous females in the final phase of the annual breeding cycle (August–October), however, some sperm was still available. In the laboratory, mating was observed, and no courtship nor postcopulatory guarding was recorded. The analysis of receptacles from laboratory experiments indicated that primiparous and multiparous females showed differences in the seasonality of mating in the first phase of the breeding cycle (September–January), related to differences in the timing of gonad maturation and hatching. Mating occurred in the final stages of gonad maturation, a short time before hatching, and matings were detected in ovigerous females. Multiple matings were also evident, to a greater extent than in the field, probably due to the higher availability of males. Females underwent over four successive spawnings in the laboratory without having to recopulate, and the incubation lasted on the average from 40 to 58 days (∼18 and 16°C respectively) and the mean duration between hatching and the next spawning was 3.4 days. It is estimated that most females carry out three successive spawnings during the annual cycle.

Decapod crustaceans are the main target species of deep water bottom trawl fisheries in the western Mediterranean. Despite their importance for fisheries and conservation, little is known about their larval development, especially in the case of deep water species. In this paper we present new information on the occurrence and morphology of larval stages for some species of commercial interest based on samples collected off the Balearic Islands. Mesozooplankton sampling was carried out using depth-stratified sampling devices at two stations located on the continental shelf break and middle slope, in the northwest and south of Mallorca in late autumn 2009 and summer 2010. We describe in detail the second mysis stage of the red shrimp Aristeus antennatus, not previously known, and the first larval stage of the slipper lobster Scyllarides latus, poorly described almost a hundred years ago. We also report the second finding of larvae of the spider crab Maja squinado and the first capture from the field of larval stages of the rose shrimp Parapenaeus longirostris and slipper lobster in the Mediterranean., Los crustáceos decápodos son especies objetivo de la pesquería de arrastre de fondo y de algunas modalidades de pesca artesanal en el Mediterráneo Occidental. A pesar de su importancia económica y la preocupación por la conservación de algunas de estas especies, la mayoría de sus estados de desarrollo larvario son desconocidos. En este trabajo se aporta nueva información sobre la presencia y la morfología de algunos estados larvarios de estas especies, a partir de muestras recolectadas alrededor de las Islas Baleares. El muestreo fue estratificado por profundidad y se realizó en dos estaciones del margen de la plataforma continental y el talud medio, situadas al norte y sur de Mallorca, durante finales de otoño de 2009 y verano de 2010. Se describe en detalle la morfología de la segunda misis de gamba roja (Aristeus antennatus), desconocida hasta la fecha, y el primer estado de desarrollo de la cigarra de mar (Scyllarides latus), descrito de manera sucinta hace casi un siglo. También se aporta información sobre el segundo hallazgo mundial de estadios larvarios de centolla (Maja squinado) y la primera vez que se capturan larvas de gamba blanca (Parapenaeus longirostris) y cigarra de mar en el medio natural del Mediterráneo.

Submitted by Patrícia Correia (patriciacorreia@ua.pt) on 2019-03-18T15:36:37Z No. of bitstreams: 1 Calado et al. - 2013 - Contrasting habitats occupied by sibling spider cr.pdf: 141251 bytes, checksum: a15079c2396191305d5f8d0b1b0d3eb3 (MD5) Approved for entry into archive by Patrícia Correia (patriciacorreia@ua.pt) on 2019-03-18T15:38:00Z (GMT) No. of bitstreams: 1 Calado et al. - 2013 - Contrasting habitats occupied by sibling spider cr.pdf: 141251 bytes, checksum: a15079c2396191305d5f8d0b1b0d3eb3 (MD5) Made available in DSpace on 2019-03-18T15:38:00Z (GMT). No. of bitstreams: 1 Calado et al. - 2013 - Contrasting habitats occupied by sibling spider cr.pdf: 141251 bytes, checksum: a15079c2396191305d5f8d0b1b0d3eb3 (MD5) Previous issue date: 2013 The authors also thank two anonymous reviewers for their constructive criticism on a previous version of this work. This work was supported by the Acção Integrada Luso-Espanhola 2010 “Dinâmica da flora microbiana intestinal e de enzimas digestivas em larvas de invertebrados marinhos num oceano em mudança à escala global” (Portugal: No. E-116/10; Spain: PT2009-0069). published